There's no hook I know of. How this is handled is partly theme dependent. If you look at the comments.php template, you should see a way to turn the page navigation on and off. That leaves the actual display of comments. This typically is done by calling wp_list_comments(). By changing the arguments array passed to this function on the template, you can override the default handling of comment listing.
Unfortunately, I don't know exactly what you need to put in the array to make your desired behavior happen. page and per_page are the array keys. Unset, false, null, 0 would be the usual value suspects. But at least you now know where to start playing around.